Title: Supertough PLA-Silane Nanohybrids by in Situ Condensation and Grafting

Abstract

Brittleness is a key barrier for poly(lactic acid) (PLA) toward broader applications. Supertough PLA was achieved by simply mixing a low amount (0.5–1 wt %) of organoalkoxysilane with PLA. Three organosilanes, (3-aminopropyl)triethoxysilane (APTES), 3-(triethoxysilyl)propyl isocyanate (ICPTES), and trimethoxymethylsilane (MTMS), were selected for this study to understand how the functional group on a silane affects the behavior of the PLA-silane hybrids. Remarkable improvements in ultimate tensile strain (up to 12 folds) and tensile toughness (up to 10 folds) were observed in APTES- and ICPTES-modified PLA without any loss in tensile strength and modulus. Glass transition temperatures measured by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) did not show any obvious decrease. We propose that in situ condensation of organosilane and grafting of PLA to form a silica-PLA core–shell nanocomplex may be the reason for the improved mechanical properties. Scanning electron microscopy (SEM) showed evidence of nanofibrils at fractured surfaces. Dynamic light scattering (DLS) indicated nanoparticle formation (bimodal, 50–200 nm and <10 nm) in dilute solution, while transmission electron microscopy (TEM) provided clearer evidence of the nanosized silica formed in situ. Rheological studies also showed increased chain entanglement in the polymer melts, which contributed to 1 order of magnitude highermore » complex viscosity and storage modulus. The simple PLA toughening strategy and the new mechanism revealed in this study will open a door to novel performance polymer materials and broader use of PLAs.« less

Authors:

Meng, Xiangtao  ^[1];

• Search DOE PAGES for author "Meng, Xiangtao"
• Search DOE PAGES for ORCID "0000-0003-3979-0655"

Nguyen, Ngoc A.  ^[1];

• Search DOE PAGES for author "Nguyen, Ngoc A."
• Search DOE PAGES for ORCID "0000-0002-0278-406X"

Tekinalp, Halil ^[2]; Lara-Curzio, Edgar  ^[1];

• Search DOE PAGES for author "Lara-Curzio, Edgar"
• Search DOE PAGES for ORCID "0000-0003-4546-5701"

Ozcan, Soydan  ^[3]

• Search DOE PAGES for author "Ozcan, Soydan"
• Search DOE PAGES for ORCID "0000-0002-3825-4589"

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Mechanical, Aerospace, Biomedical Engineering
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Mechanical, Aerospace, Biomedical Engineering

Publication Date:

Wed Dec 06 00:00:00 EST 2017

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Manufacturing Office; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division

OSTI Identifier:

1474444

Alternate Identifier(s):

OSTI ID: 1476428

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

ACS Sustainable Chemistry & Engineering

Additional Journal Information:

Journal Volume: 6; Journal Issue: 1; Journal ID: ISSN 2168-0485

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 77 NANOSCIENCE AND NANOTECHNOLOGY; Alkoxysilane; Cross-linking; Mechanical property; PLA nanocomposites; Polylactide; Rheology; Sustainable material